Title

Author

Date of Award

1990

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Psychology

First Advisor

William F. Waters

Abstract

Stress is hypothesized to cause increased cognitive and physiological arousal which is incompatible with sleep. Major life events have been implicated as a significant factor in the onset of chronic insomnia (Healey et al., 1981), and there is some suggestion that minor life events influence symptoms as well (Haynes et al., 1981). The present study was designed to evaluate and further clarify the role of daily minor stressors and mood variables on sleep in both normal sleepers and insomniacs. Subjects with insomnia secondary to medical or physical disorders were excluded from this study. Fifty-four adult subjects (20 mixed-complaint insomniacs, 17 sleep onset insomniacs, and 17 normal sleepers) volunteered from the community. Each subject completed the Daily Stress Inventory, the State-Trait Anxiety Inventory (State Form) and the Zung Self-rating Scale for Depression each night between supper and retiring. They completed a Daily Sleep Diary in the morning upon awakening, and mailed back completed forms daily. In this manner, 21 consecutive days of monitoring were collected for each subject. Stress was divided into two conditions; the seven days with the highest stress scores for each individual became the high stress condition, and the seven days with the lowest stress scores became the low stress condition for each individual. Results comparing sleep disturbances on those days indicated that under relatively high stress conditions, subjects slept fewer minutes, achieved a lower quality of sleep and lower sleep efficiency than they did in the low stress condition. There was a significant group by stress interaction such that all insomniacs slept fewer minutes under the high stress condition than under the low stress condition, but normal subjects showed no change across stress conditions. Regression analyses indicated that frequency of daily minor stressors was predictive of latency to sleep onset and difficulty falling asleep. Depression scores were predictive of latency to sleep onset, difficulty falling asleep, restedness upon awakening and sleep efficiency. Depression scores were substantially more predictive of dependent sleep measures than anxiety scores were. Results lend modest support to the hypothesis that stress contributes to symptoms of insomnia. Additional theoretical and clinical implications are discussed.